Flexible polymer concrete and methods for making flexible polymer concrete

ABSTRACT

A composition that sets to produce a concrete includes Portland cement; a polymerizable material having bubbles dispersed in the polymerizable material; an aggregate; and water in a sufficient amount such that the composition sets to a concrete. A method for making a concrete article uses a paste that includes Portland cement and a polymerizable material having bubbles dispersed in the polymerizable material. The paste is added to an aggregate to create a settable composition, and the settable composition is allowed to set to a concrete article.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 14/513,296 filed Oct. 14, 2014.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to flexible Portland cement polymer concrete andmethods for making flexible Portland cement polymer concrete.

2. Description of the Related Art

Conventional concrete is a dense hard hydrated mass produced frommixtures of Portland cement, coarse aggregate, fine aggregate, andwater. Concrete mixtures generally use only sufficient water to make themixture workable for placement and to yield hardened concrete having acompressive strength of at least 8.3 MPa (1200 psi) after 28 days.Portland cement is a well known cement that upon mixing with water bindsor unites the other materials present in the mixture into concrete. ThePortland cement is typically a Type I, II, III, IV and V Portland cementas defined in ASTM C 150. The coarse aggregate conventionally comprisesparticles such as gravel, quartzite, granite, limestone, shale, andother minerals having a particle size greater than 9.5 millimeters(0.375 inches). The fine aggregate employed in Portland cement concretesis most often sand comprised of particles less than about 0.375 inches(9.5 millimeters) in size, typically equal to or less than about 0.1875inches (4.76 millimeters) in size. Typically, fresh concrete has mixingwater exceeding the amount needed for hydration for purposes ofworkability, handling, and finishing.

There are many reasons for the popularity of concrete. It is relativelyinexpensive, capable of taking on the shape of a mold, has exceptionallyhigh compression strength and is very durable. However, as a building orconstruction material, concrete, whether it is reinforced or not, hascertain disadvantages. One disadvantage is that concrete has relativelylow tensile strength and therefore has little ability to flex withoutcracking.

A concrete road surface is a good example where concrete, under repeatedloads and flexing due to vehicle traffic, eventually degrades, leadingto cracks. This illustrates two primary limitations of Portland cementconcrete. The first fundamental limitation is a relatively low tensilestrength which primarily exhibits itself as cracks in concrete products.This limitation is addressed by adding reinforcement to the concretetypically in the form of steel fibers, steel bars or steel mesh and/orby controlling the cracking through predetermined crack locations.However, concrete structures can require large amounts of reinforcingmaterial, thereby significantly increasing labor and material costs. Thesecond fundamental limitation is that water intrusion into the concretecan cause both physical damage during freezing and thawing and chemicaldamage by instigating a series of secondary chemical reactions that cancause degradation of the concrete matrix. This type of behavior cancause surface scaling, cracking and crumbling of concrete much earlierthan weather and age might be expected to cause similar degradation.Concrete that has a greater tensile strength, and is thereby able toflex more without failing, would result in surfaces and structures thatare less susceptible to wear and cracking.

What is needed therefore is a method for making a concrete havinggreater tensile strength without requiring the addition of reinforcingmaterials.

SUMMARY OF THE INVENTION

The present invention provides a composition that sets to produce aconcrete. The composition includes Portland cement; a polymerizablematerial having bubbles dispersed in the polymerizable material; anaggregate; and water in a sufficient amount such that the compositionsets to a concrete having a compressive strength of at least 8.3 MPa(1200 psi).

The present invention also provides a method for making a concretearticle. In the method, a paste is prepared that includes Portlandcement and a polymerizable material having bubbles dispersed in thepolymerizable material; the paste is combined with an aggregate tocreate a settable composition; and the settable composition is allowedto set to a concrete article.

The present invention also provides a method for producing microbubblesin a polymerizable material. The method includes the steps of: (a)incorporating a gas into a polymerizable material thereby creatingbubbles in the polymerizable material, wherein the bubbles contain thegas; and (b) feeding the polymerizable material through a nozzle toreduce an average diameter of the bubbles.

It is an advantage of the invention to provide a concrete having greatertensile strength and flexibility. The invention provides greater tensilestrength without requiring the addition of metallic reinforcingmaterials. The concrete of the present invention is able to flex morewithout failing thereby resulting in articles and structures that areless susceptible to wear, cracking, and failure.

In the flexible Portland cement polymer concrete of the invention,embedded in the hydrated Portland cement matrix are very small sphericalgas bubbles, mostly in the size range of 0.0001 to 0.0005 inchesdiameter. Each gas filled bubble is surrounded by a polymeric material,such as polystyrene. Bubbles and paste mixed during manufacture fill thespaces between aggregate (sand/gravel) elements. Applied forcestransferred through the concrete structure deform the bubble shapeallowing the material to flex or bend.

Mixes are designed for the product being developed. In one exampleembodiment, a portion of the cement paste of a conventional concrete(10% to 30% by volume) is replaced with an equal volume ofstyrene/polystyrene resin. Polymerization is heat initiated and usesPortland cement and monomer latent heat exotherm to accelerate curing.

The flexible Portland cement polymer concrete of the invention is mixedand placed using conventional equipment modified to conform to themethod of the invention. Following placement of the mixed concretematerial, the resin is polymerized in situ as the Portland cement pastehydrates. The splitting tensile strength of the flexible Portland cementpolymer concrete of the invention may be about 40% of compressivestrength. Since polystyrene in the finished product fills most voids inthe matrix, liquid absorption is small (<1%).

The flexible Portland cement polymer concrete of the invention is formedusing a paste designed to replace standard Portland cement paste in avariety of products. Since the flexible Portland cement polymer concreteof the invention has useable tensile strength, steel reinforcing may bereduced or eliminated in many products. Pre-stressing concrete increasesdesign tensile strength in a plane perpendicular to pre-stressdirection. In many applications, a requirement to pre-stress may beeliminated. The flexible Portland cement polymer concrete of theinvention increases tensile strength in all directions.

One potential application that may be improved with the increasedtensile strength and reduced liquid absorption of the flexible Portlandcement polymer concrete of the invention is railroad crossties. Theflexible Portland cement polymer concrete can produce railroad crosstieswhich have extended service life reducing maintenance costs. Most woodrailroad crossties fail in service from plate cutting or spike killcausing gauge widening and requiring continual maintenance. The industryreplaces ties using a spot maintenance procedure. When a section oftrack is scheduled for maintenance (about every seven years), workersremove those individual ties not expected to last to the next cycle andreplace them with new treated ties. Wood railroad ties are flexible.When a train passes over them, ties flex and transfer the rolling loadto the ballast road bed. To service this market, a replacement railroadcrosstie can be manufactured using the flexible Portland cement polymerconcrete of the invention. A railroad crosstie manufactured using theflexible Portland cement polymer concrete can: (i) flex like a wood tiewithout cracking; (ii) hold gauge; (iii) occupy the same space(7″×9″×102″); (iv) improve lateral track stability; (v) employ anintegral rail seat; (vi) use a track spike and rail anchor fasteningsystem; (vii) have a longer service life; and (viii) be installed usingcurrent track maintenance equipment and procedures.

Another potential application that may be improved with the flexiblePortland cement polymer concrete of the invention is roof tiles. A rooftile manufactured using the flexible Portland cement polymer concrete,can have a tile weight reduced 40% to 50% compared to conventionalPortland cement concrete. A roof tile manufactured using the flexiblePortland cement polymer concrete may have: (i) lower tile weight therebyreducing freight costs; (ii) reduced roof structure supportrequirements; (iii) reduced weather damage from wind and hail; and (iv)lower absorption thereby reducing long term freeze/thaw damage.

Another potential application that may be improved with the flexiblePortland cement polymer concrete of the invention is bridge decks. Whentraveling American highways, bridge decks are observed under repaireverywhere. In some cases, bridges require resurfacing in as little asfive years. Bridges constructed with conventional Portland cementconcrete decks flex under traffic loads. This flexing leads to stresscrack proliferation. Cracks lead to freeze/thaw deterioration. Applieddeicing chemicals corrode reinforcing steel leading to potholeformation. Building bridge decks using the flexible Portland cementpolymer concrete of the invention may eliminate most stress cracks thusextending deck life and reducing maintenance costs. Deck thickness andreinforcing steel could possibly be cut in half while improving decklongevity.

Another potential application that may be improved with the flexiblePortland cement polymer concrete of the invention is highway pavement.Conventional Portland cement concrete highway pavement lasts on averageabout 30 years. During this period, brittle concrete develops cracks(see bridge deck discussion above). Reinforcing steel corrodes fromwater and applied chemicals and potholes develop. A variety of remedialmeasures are applied to smooth the running surface. When the surface issufficiently degraded, an asphalt topping may be applied to extend roadlife. It is contemplated that a two inch layer of the flexible Portlandcement polymer concrete of the invention could be applied to aconventional Portland cement concrete pavement because the flexiblePortland cement polymer concrete can bond to the existing concretesurface. Full depth highway pavement built using the flexible Portlandcement polymer concrete of the invention will flex under load and reduceor eliminate cracks. The flexible Portland cement polymer concrete hasuseable tensile strength (about equal to pre-stressed conventionalPortland cement concrete). It is anticipated that pavements using theflexible Portland cement polymer concrete of the invention may bedesigned to have a thinner section and will eliminate/reduce steelreinforcing requirements. Saw cut segments may be eliminated or spacedfarther apart. If elevated temperature curing is selected for highwayspot maintenance projects, drive on load capacity may be achieved in aslittle as twelve hours.

Another potential application that may be improved with the flexiblePortland cement polymer concrete of the invention is concrete blocksmanufactured using minimum water to hydrate cement. Since blocks aresteam cured, it may be possible to utilize the flexible Portland cementpolymer concrete of the invention to improve flexure strength. Pasteingredients are combined in a separate mixer in the method of theinvention. Paste can be combined with aggregate in a final mixing stage.Standard forming and curing methods can be used.

Another potential application that may be improved with the flexiblePortland cement polymer concrete of the invention is concrete pipe. Someconcrete pipe is dry cast like concrete blocks and could utilize similarcasting and curing methods. Other pipe is wet cast and would employstandard precast methods modified conforming to method of the invention.Since the flexible Portland cement polymer concrete of the inventionbonds to conventional Portland cement concrete, large cast pipe sectionscould be lined with the flexible Portland cement polymer concrete in aseparate operation utilizing its unique low absorption.

Other potential applications that may be improved with the flexiblePortland cement polymer concrete of the invention include, withoutlimitation: precast products; earthquake resistant structures; drillpipe grout; and surface cladding.

These and other features, aspects, and advantages of the presentinvention will become better understood upon consideration of thefollowing detailed description, drawings and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a scanning electron microscope (SEM) micrograph taken at 130×of a concrete sample made according to the present invention.

FIG. 2 is an SEM micrograph taken at 480× of a concrete sample madeaccording to the present invention.

FIG. 3 is an SEM micrograph taken at 150× of a concrete sample madeaccording to the present invention.

FIG. 4 is an SEM micrograph taken at 280× of a concrete sample madeaccording to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

One embodiment of the present invention is a composition that sets toproduce a concrete. The composition includes Portland cement (e.g., aType I, II, III, IV and V Portland cement); a polymerizable materialhaving bubbles dispersed in the polymerizable material; an aggregate;and water in a sufficient amount such that the composition sets to aconcrete having a compressive strength of at least 8.3 MPa (1200 psi).

In one version of the composition, the composition comprises: from about10% to about 40% by weight of Portland cement; from about 1% to about20% by weight of the polymerizable material; from about 40% to about 80%by weight of the aggregate; and from about 1% to about 20% by weight ofwater, wherein all weight percentages are percent by weight of the totalcomposition. In another version of the composition, the compositioncomprises: from about 20% to about 30% by weight of Portland cement;from about 2% to about 10% by weight of the polymerizable material; fromabout 50% to about 70% by weight of the aggregate; and from about 5% toabout 15% by weight of water, wherein all weight percentages are percentby weight of the total composition.

In one version of the composition, the composition sets to a concretehaving a ratio of splitting tensile strength to compressive strength of0.15 or greater. In another version of the composition, the compositionsets to a concrete having a ratio of splitting tensile strength tocompressive strength of 0.3 or greater. In yet another version of thecomposition, the composition sets to a concrete having a ratio ofsplitting tensile strength to compressive strength of 0.4 or greater.

In one version of the composition, the composition sets to a concreteincluding cells having an average inside diameter of 0.0005 inches orless. In another version of the composition, the composition sets to aconcrete including cells having an average inside diameter of 0.0003inches or less. In yet another version of the composition, thecomposition sets to a concrete including cells having an average insidediameter of 0.0001 inches or less.

In one version of the composition, the polymerizable material has 5% to33% solids by volume. In another version of the composition, thepolymerizable material has 5% to 20% solids by volume. In yet anotherversion of the composition, the polymerizable material has 5% to 15%solids by volume.

In one version of the composition, the polymerizable material comprisesa styrene monomer. In another version of the composition, thepolymerizable material comprises a styrene monomer and polystyrene. Inyet another version of the composition, the polymerizable materialcomprises polystyrene and a styrene monomer in a ratio of polystyrene tostyrene monomer in the range of 1:2 to 1:20, or 1:3 to 1:10, or 1:3 to1:5.

In one version of the composition, the aggregate is selected from coarseaggregate, fine aggregate, and mixtures thereof. The coarse aggregatemay comprise particles such as gravel, quartzite, granite, limestone,shale, and other minerals having a particle size greater than 9.5millimeters (0.375 inches). The fine aggregate may comprise sand havingparticles less than about 0.375 inches (9.5 millimeters) in size,typically equal to or less than about 0.1875 inches (4.76 millimeters)in size.

In one version of the composition, the bubbles dispersed in thepolymerizable material have an average inside diameter of 0.0005 inchesor less. In another version of the composition, the bubbles dispersed inthe polymerizable material have an average inside diameter of 0.0003inches or less. In yet another version of the composition, the bubblesdispersed in the polymerizable material have an average inside diameterof 0.0001 inches or less. The bubbles dispersed in the polymerizablematerial may contain a gas consisting essentially of nitrogen. Thebubbles dispersed in the polymerizable material may contain a gasessentially free of oxygen. The bubbles dispersed in the polymerizablematerial may contain air.

In one version of the composition, the composition includes asuperplasticizer such as a sulfonated melamine-formaldehyde condensate,a sulfonated naphthalene-formaldehyde condensate, a modifiedlignosulfonate, or a polycarboxylate derivative.

In one version of the composition, the composition further includes apolymerization initiator for the polymerizable material. Suitablestyrene initiators include, for example, benzoyl peroxide,azobisisobutyronitrile, dibenzoyl peroxide, tert-butyl perbenzoate,dicumyl peroxide, di-tert-butyl peroxide and mixtures thereof.

Another embodiment of the present invention is a method for making aconcrete article. In the method, a paste is prepared that includeswater, Portland cement, and a polymerizable material having bubblesdispersed in the polymerizable material; the paste is combined with anaggregate to create a settable composition; and the settable compositionis allowed to set to a concrete article. Preferably, the aggregate isadded to the paste.

In one version of the method for making a concrete article, the bubblesare dispersed in the polymerizable material before adding thepolymerizable material to the Portland cement paste. The bubbles can bedispersed in the polymerizable material using a high shear mixer. Thebubbles dispersed in the polymerizable material have an average insidediameter of 0.0005 inches or less, or 0.0003 inches or less, or 0.0001inches or less. The bubbles dispersed in the polymerizable material maycontain (i) a gas consisting essentially of nitrogen or (ii) a gasessentially free of oxygen, or (iii) air.

In one version of the method for making a concrete article, thepolymerizable material has 5% to 33% solids by volume. In anotherversion of the method, the polymerizable material has 5% to 20% solidsby volume. In yet another version of the method, the polymerizablematerial has 5% to 15% solids by volume.

In one version of the method for making a concrete article, thepolymerizable material comprises a styrene monomer. In another versionof the method, the polymerizable material comprises a styrene monomerand polystyrene.

In yet another version of the method, the polymerizable materialcomprises polystyrene and a styrene monomer in a ratio of polystyrene tostyrene monomer in the range of 1:2 to 1:20, or 1:3 to 1:10, or 1:3 to1:5. In one version of the method, the polymerizable material replaces15% to 30% by volume of the Portland cement paste in a conventionalconcrete mixture.

Another embodiment of the present invention is a method for producingmicrobubbles in a polymerizable material. The method includes the stepsof: (a) incorporating a gas into a polymerizable material therebycreating bubbles in the polymerizable material, wherein the bubblescontain the gas; and (b) feeding the polymerizable material through anozzle to reduce an average diameter of the bubbles. The nozzle may havean orifice of 0.0100 inches to 0.0225 inches in inside diameter.

In one version of the method for producing microbubbles in apolymerizable material, the polymerizable material comprises a styrenemonomer. In another version of the method, the polymerizable materialcomprises a styrene monomer and polystyrene. In yet another version ofthe method, the polymerizable material comprises polystyrene and astyrene monomer in a ratio of polystyrene to styrene monomer in therange of 1:2 to 1:20, or 1:3 to 1:10, or 1:3 to 1:5. In one version ofthe method, the polymerizable material has 5% to 33% solids by volume.In another version of the method, the polymerizable material has 5% to20% solids by volume. In yet another version of the method, thepolymerizable material has 5% to 15% solids by volume.

In another version of the method for producing microbubbles in apolymerizable material, after feeding the polymerizable material throughthe nozzle to reduce an average diameter of the bubbles, the bubbles inthe polymerizable material can have an average inside diameter of 0.0005inches or less, or 0.0003 inches or less, or 0.0001 inches or less. Thebubbles dispersed in the polymerizable material may contain (i) a gasconsisting essentially of nitrogen or (ii) a gas essentially free ofoxygen, or (iii) air.

In one non-limiting example embodiment, the invention incorporates ameans to form and disperse polystyrene bubbles in a Portland cementpaste. The bubble size range can be 0.0001 to 0.0005 inches (insidediameter) uniformly dispersed in the paste mix. The method can be atwo-step process where a gas (e.g., air, nitrogen, or a gas essentiallyfree of oxygen) is first entrained in a styrene/polystyrene resin usinga high shear (blender) mixer. Bubble size at this stage will be in the0.010 to 0.030 inch range, visible unmagnified.

The second step passes this aerated mixture through a positivedisplacement pump operating at 1000 to 3000 psig, or 1000 to 2000 psig,or at about 1500 psig. Following Boyle's law, the entrained bubblescompress. The discharge from the pump is through a spray dry nozzleorifice of typically 0.0100 to 0.0225 inches in diameter, or at about0.0135 inches in diameter. As the compressed bubbles transit the nozzleto ambient pressure, the bubbles expand very rapidly and form very smallspheres which are then dispersed onto a moving cement paste surface. Ittakes 216,000 bubbles at 0.0005 inches diameter to equal one bubble at0.030 inches diameter. [D³/d³].

Once dispersed in the cement paste, the resin is cured in situ,optionally using elevated temperature curing. Non-limiting exampleelevated curing temperatures are 100° F. to 200° F.

The method of the invention controls the bubble size structure. It isthese small gas filled voids that make the Portland cement polymerconcrete flexible.

In another non-limiting example embodiment, a mixer such as thatdescribed in U.S. Pat. No. 4,063,715 (in which the inventor of thepresent disclosure is a named inventor, and which is incorporated hereinby reference) is used to mix the concrete composition. In yet anothernon-limiting example embodiment, a casting process such as thatdescribed in U.S. Pat. No. 3,493,644 (in which the inventor of thepresent disclosure is a named inventor, and which is incorporated hereinby reference) is used to cast concrete articles from the concretecomposition described herein.

The invention is further illustrated in the following Example which ispresented for purposes of illustration and not of limitation.

Example

Table 1 lists general mix parameters for a concrete according to theinvention.

TABLE 1 General Mix Total Aggregate 40 weight % to 80 weight % PortlandCement 10 weight % to 40 weight % Water 1 weight % to 20 weight %Superplasticizer 0.1 weight % to 2 weight % Styrene Resin 1 weight % to20 weight % Nitrogen Void Volume 5 to 30 volume % of paste Total Paste20 weight % to 60 weight % Water/Cement Ratio by weight 0.02 to 2.0Resin/Paste Ratio by volume 0.01 to 1.0 Gas Void Ratio to Resin Volume0.3 to 0.7

Table 2 lists one non-limiting example mix for a concrete according tothe invention.

TABLE 2 Example Mix Weight Material (lbs.) Weight % Volume % Aggregate -Sand 11.0000 57.53% Total Aggregate 11.0000 57.53% Portland Cement TypeOne 5.0000 26.15% Water 2.0000 10.46% Superplasticizer (naphthalene-0.0943 0.49% formaldehyde condensate) Styrene Resin = 1.0249 5.36% 1part polystyrene - 4 parts styrene monomer Nitrogen Void Volume 10% ofpaste Total Paste 8.1193 42.47% Mix Total 19.1193 Water/Cement Ratio byweight 0.4000 Resin/Paste Ratio by volume 0.3000 Nitrogen Void Ratio toResin Volume 0.5000

An example method for making trial specimens of a flexible Portlandcement polymer concrete according to the invention proceeds as follows.The equipment used is modified standard commercial mixers and pump.Materials used are washed concrete sand and gravel, Type I Portlandcement, water, styrene/polystyrene polymerizable resin,naphthalene-formaldehyde condensate (superplasticizer), benzoyl peroxide(polymerization initiator), azobisisobutyronitrile (azobispolymerization initiator), and nitrogen.

Resin Preparation & Apparatus

Use a polyethylene container and a stirring device. Dissolve one parthigh molecular weight polystyrene (Americas Styrenics StyronR 685D orNOVA-Dylark332) in four parts of inhibited styrene monomer. Store theprepared resin in a closed container with air space at top below 40° F.

Portland Cement Preparation

Ground Portland cement is about 50% air containing oxygen. Oxygen reactswith the inhibitor in styrene monomer preventing polymerization.Stripping the oxygen from the air in the cement will allow the resin topolymerize in situ. Measure the cement into a suitable container (4″×8″mold for example), cover the top with cloth filter, and inject lowpressure (>15 psig) nitrogen into the bottom of the container. Escapingnitrogen carries the oxygen with it.

Mix Design

Use the Table 2 Mix above.

Step One Mix Apparatus

This non-limiting example method uses three separate mixing devices. Thefirst is a 64 oz. commercial blender (Waring HGB150). The blender isfitted with a nitrogen purge inlet replacing air in the container withnitrogen at atmospheric pressure. Purge is run continuously prior to andduring mixing. The blender is operated at high speed entraining nitrogen(up to 50% by volume) in the resin. Large bubbles will coalesce andescape at the upper surface. Small bubbles will be retained in theresin.

Mix Step One

Into a clean container, measure one and one half times the weight ofresin calculated in the mix design of Table 2. Calculate the weight ofstyrene in resin. Add 1% on styrene weight of benzoyl peroxide plus 200ppm azobis to the resin. Pour the contents into step one blendercontainer. Close cover and purge with nitrogen two minutes. Blend onhigh for 1½ minute. Stop and allow to rest 4% minutes.

Step Two Mix Apparatus

Step two is done in a one gallon Waring CB15V one gallon variable speedblender (simulating the mixer in U.S. Pat. No. 4,063,715) fitted with anitrogen purge inlet replacing air in the container with nitrogen atatmospheric pressure. Purge is run continuously prior to and duringmixing.

Next to the blender is a Graco Magnum X7 Sprayer Model 262805 Series Cpump. Suction is from a 1000 ml PP Conical Graduate (U S Plastics stock#77376). A discharge hose is connected to a nozzle (Spraying SystemsSpray Dry 1/4SX-MFP-SIYM80 orifice). The nozzle discharge is directeddownward into the center opening of the blender canister. The nozzle ismounted on a funnel bracket at end of discharge hose. It is placed intop opening of the CB15V when ready for resin transfer.

Since step two is done at elevated temperature, the canister is filledwith boiling water and let stand ten minutes to preheat, and thenemptied prior to start.

Mix Step Two

Styrene rate of polymerization is a function of the temperature. Part ofthe heat required to start polymerization comes from the mixing water.

Pour resin from step one into the 1000 ml graduate. Jog cycle the pumpto fill the lines with resin. Mark graduate resin top face start andstop levels.

Start nitrogen purge.

Mix design weight of water is heated to about 205° F. and mixed withsuperplasticizer. Pour this water mix into the heated blender canister.Start blender at slow speed. Add Portland cement slowly forming aslurry. Increase speed to form a vortex.

Place nozzle discharge bracket into canister top opening. Start pump andobserve draw down in graduate. When specimen size is reached, stop pump.Mix additional 45 seconds. Stop blender.

Step Three Mix Apparatus

Final mixing is done in a Hobart 12 quart mixer. The mixer bowl ispreheated by filling with boiling water and let stand 10 minutes. Thebowl is emptied prior to step three.

Mix Step Three

Heat is added to the mix in step three. Aggregate sample is weighed andplaced in a metal container which is oven heated to 205° F. Four ouncesof water is poured over the aggregate to flash off any hot spots.

Paste content of blender canister is poured into step three bowl. Hobartmixer is started on slow speed. Hot aggregate is added slowly. Mixadditional 2% minutes. Stop mixer three. Record mix temperature.

Place Concrete

The mix design should make enough material to fill two 4″×8″ cylindermolds (requires about 8 pounds per mold). Transfer the hot mix intomolds. Rod or vibrate as necessary to consolidate mix in molds. Finishby capping molds. Place in oven controlled to 180° F. for six to eighthours. Remove and air cool.

Test Specimen

Run several two specimen runs of initial mix design. Test at 14 days.From each batch, test one cylinder for compression strength using ASTMC39 (Standard Test Method for Compressive Strength of CylindricalConcrete Specimens), and test one cylinder for splitting tensilestrength using ASTM C496 (Standard Test Method for Splitting TensileStrength of Cylindrical Concrete Specimens).

FIGS. 1 to 4 show scanning electron microscope micrographs of a concretesample made according to the present invention.

Thus, the invention provides flexible Portland cement polymer concreteand methods for making flexible Portland cement polymer concrete.

Although the invention has been described in considerable detail withreference to certain embodiments, one skilled in the art will appreciatethat the present invention can be practiced by other than the describedembodiments, which have been presented for purposes of illustration andnot of limitation. Therefore, the scope of the appended claims shouldnot be limited to the description of the embodiments contained herein.

What is claimed is:
 1. A composition that sets to produce a concrete,the composition comprising: Portland cement; a polymerizable materialhaving bubbles dispersed in the polymerizable material; an aggregate;and water in a sufficient amount such that the composition sets to aconcrete, wherein the polymerizable material comprises polystyrene and astyrene monomer in a ratio by weight of polystyrene to styrene monomerin a range of 1:2 to 1:20.
 2. The composition of claim 1 wherein: thepolymerizable material comprises polystyrene and a styrene monomer in aratio by weight of polystyrene to styrene monomer in a range of 1:3 to1:10.
 3. The composition of claim 1 wherein: the polymerizable materialcomprises polystyrene and a styrene monomer in a ratio by weight ofpolystyrene to styrene monomer in a range of 1:3 to 1:5.
 4. Acomposition that sets to produce a concrete, the composition comprising:Portland cement; a polymerizable material having bubbles dispersed inthe polymerizable material; an aggregate; and water in a sufficientamount such that the composition sets to a concrete, wherein thepolymerizable material comprises a styrene monomer and polystyrene, andwherein the polymerizable material has 5% to 33% solids by volume. 5.The composition of claim 4 wherein: the polymerizable material has 5% to20% solids by volume.
 6. A composition that sets to produce a concrete,the composition comprising: Portland cement; a polymerizable materialhaving bubbles dispersed in the polymerizable material; an aggregate;and water in a sufficient amount such that the composition sets to aconcrete, and wherein the composition sets to a concrete includingbubbles with cell walls having an average inside diameter of 0.0005inches or less.
 7. The composition of claim 6 wherein the compositioncomprises: from about 10% to about 40% by weight of Portland cement;from about 1% to about 20% by weight of the polymerizable material; fromabout 40% to about 80% by weight of the aggregate; and from about 1% toabout 20% by weight of water, wherein all weight percentages are percentby weight of the total composition.
 8. The composition of claim 6wherein the composition comprises: from about 20% to about 30% by weightof Portland cement; from about 2% to about 10% by weight of thepolymerizable material; from about 50% to about 70% by weight of theaggregate; and from about 5% to about 15% by weight of water, whereinall weight percentages are percent by weight of the total composition.9. The composition of claim 8 wherein: the composition sets to aconcrete having a ratio of splitting tensile strength to compressivestrength of 0.15 or greater.
 10. The composition of claim 8 wherein: thecomposition sets to a concrete having a ratio of splitting tensilestrength to compressive strength of 0.3 or greater.
 11. The compositionof claim 8 wherein: the composition sets to a concrete having a ratio ofsplitting tensile strength to compressive strength of 0.4 or greater.12. The composition of claim 1 wherein: the composition sets to aconcrete including bubbles with cell walls having an average insidediameter of 0.0003 inches or less.
 13. The composition of claim 1wherein: the composition sets to a concrete including bubbles with cellwalls having an average inside diameter of 0.0001 inches or less. 14.The composition of claim 1 wherein: the polymerizable material comprisesa styrene monomer and polystyrene.
 15. The composition of claim 14wherein: the polymerizable material has 5% to 33% solids by volume. 16.The composition of claim 6 wherein: the bubbles dispersed in thepolymerizable material contain a gas selected from the group consistingof a gas consisting essentially of nitrogen, a gas essentially free ofoxygen, and air.
 17. The composition of claim 6 wherein: the bubblesdispersed in the polymerizable material have an average inside diameterof 0.0005 inches or less.
 18. The composition of claim 6 wherein: thebubbles dispersed in the polymerizable material have an average insidediameter of 0.0003 inches or less.
 19. The composition of claim 6wherein: the composition further includes a polymerization initiator forthe polymerizable material.
 20. The composition of claim 6 wherein: thecomposition further includes a superplasticizer.